There is known a vehicular shift control apparatus configured to implement shifting actions of a belt-type transmission having a pair of variable-diameter pulleys and a transmission belt connecting the pair of variable-diameter pulleys, by a hydraulic pressure control to change effective diameters of the above-indicated pair of variable-diameter pulleys (diameters of the pulleys at which the transmission belt engages the pulleys). Patent Document 1 discloses an example of such a shift control apparatus for a belt-type transmission. The shift control apparatus for the belt-type transmission disclosed in this Patent Document 1 is configured such that the regulation valve regulates supply hydraulic pressures to be respectively applied to the pair of variable-diameter pulleys, according to respective commanded hydraulic pressure values, for implementing a shifting action of the belt-type transmission such that a speed ratio of the transmission coincides with a target value, and such that the above-indicated transmission belt does not slip on the above-indicated variable-diameter pulleys. One of the above-indicated pair of variable-diameter pulleys, which is a driving-side variable-diameter pulley, includes a hydraulic cylinder provided to receive the supply hydraulic pressure. The hydraulic cylinder has a working oil supply port provided with a supply-side check valve for inhibiting a discharge flow of the working oil, and a working oil discharge port provided with a discharge-side check valve which is switchable from its working oil discharge inhibiting state to its working oil discharge permitting state, upon an operation of a hydraulic actuator. The shift control apparatus disclosed in the above-described Patent Document 1 operates the above-indicated hydraulic actuator to permit the discharge flow of the working oil from the hydraulic cylinder of the above-indicated driving-side variable-diameter pulley, when a predetermined condition for permitting the discharge flow of the working oil is satisfied.